Hydraulic piston apparatus

Abstract

A variable capacity hydraulic constant stroke piston apparatus has an annular rotor rotatably mounted for rotation around an axis of rotation and having a plurality of radial cylinder bores therein spaced at intervals therearound with working liquid inlets and outlets at the radially outer ends thereof, a rotor drive for rotating said rotor around the axis of rotation, an eccentric cam positioned within the rotor and movable along a circular locus of eccentric positions concentric with said axis of rotation; a device for fixing the eccentric cam at one of the plurality of eccentric positions and for moving the eccentric cam around the axis of rotation between said positions; a plurality of pistons radially reciprocally movably mounted in corresponding cylinder bores in the rotor, the pistons having heads normally contacting an outer periphery of the eccentric cam and moving through a constant length stroke at each position of the cam; and working liquid current rectifying means connected between the inlets and outlets of the cylinder bores and an inlet and outlet from the apparatus for supplying working liquid to the cylinders and receiving working liquid from the cylinders in a reciprocating flow and rectifying and smoothing the flow at the inlet and outlet of the apparatus. Alternatively the cam can be fixed and the stator movable through and fixable at one of the eccentric positions.

What is claimed is: 
     
       1. A variable capacity hydraulic constant stroke piston apparatus comprising: an annular rotor rotatably mounted for rotation around an axis of rotation and having a plurality of radial cylinder bores therein spaced at intervals around said rotor, said cylinder bores having working liquid inlet and outlet means at the radially outer ends thereof;   rotor drive means connected to said rotor for rotating said rotor around said axis of rotation;   an eccentric dam positioned within said rotor and movable along a circular locus of eccentric positions, said circular locus being concentric with said axis of rotation;   means fixing said eccentric cam within said rotor at one of said plurality of eccentric positions and for moving said eccentric cam around said axis of rotation between said positions;   a plurality of pistons radially reciprocally movably mounted in corresponding cylinder bores in said rotor, said pistons having heads normally contacting an outer periphery of said eccentric cam and moving through a constant length stroke at each position of said cam; and   working liquid current rectifying means connected between said inlet and outlet means of said cylinder bores and an inlet and outlet from said apparatus for supplying working liquid to said cylinders and receiving working liquid from said cylinders in a reciprocating flow and rectifying and smoothing said flow at the inlet and outlet of said apparatus.   
     
     
       2. A hydraulic piston apparatus as claimed in claim 1 further comprising a stator concentrically mounted in a fixed positon around said rotor, said stator having said inlet and outlet from said apparatus therein spaced around said rotor, and said working liquid current rectifying means comprises passage means along said stator from positions around the interior of said stator to said inlet and outlet from said apparatus. 
     
     
       3. A variable capacity hydraulic constant stroke piston apparatus comprising: an annular rotor rotatably mounted for rotation around an axis of rotation and having a plurality of radial cylinder bores therein spaced at intervals around said rotor, said cylinder bores having working liquid inlet and outlet means at the radially inner ends thereof:   rotor drive means connected to said rotor for rotating said rotor around said axis of rotation;   a fixed shaft positioned concentrically within said rotor;   an eccentric stator mounted around said rotor and movable along a circular locus of eccentric positions, said circular locus being concentric with said axis of rotation;   means fixing said stator around said rotor at one of said plurality of eccentric positions and for moving said stator around said axis of rotation between said positions;   a plurality of pistons radially reciprocally movably mounted in corresponding cylinder bores in said rotor, said pistons having heads normally contacting an inner periphery of said stator and moving through a constant length stroke at each position of said stator; and   working liquid current rectifying means connected between said inlet and outlet means of said cylinder bores and an inlet and outlet from said apparatus for supplying working liquid to said cylinders and receiving working liquid from said cylinders in a reciprocating flow and rectifying and smoothing said flow at the inlet and outlet of said apparatus.   
     
     
       4. A hydraulic piston apparatus as claimed in claim 3 in which said working liquid current rectifying means comprises passages along said fixed shaft from positions around the interior of said rotor to the inlet and outlet from said apparatus.